Surgical site infections (SSIs) are a well-known potential complication of surgery. They are assocaited with preoperative malnutrition and lead to increased medical costs and longer hospital stays. Therefore, surgeons should appropriately identify patients who are at a high risk. The geriatric nutritional risk index (GNRI) is a tool, increasingly utilized to assess the degree of malnutrition, particularly in elderly patients. Therefore, the present study attempted to validate whether GNRI could predict the risk of SSI in patients following pancreaticoduodenectomy (PD). A cohort study was retrospectively conducted on 106 patients in the Department of Digestive Surgery, Kawaguchi Municipal Medical Center, Japan from January 2007 to December 2017. All patients were subjected to nutritional screening using GNRI and followed up for the occurrence of postoperative complications, including SSI post PD. Additionally, risk factors for developing SSI, and the patient's height, body mass index and preoperative laboratory values were documented. Patients were divided into SSI (n=15) and non-SSI (n=91) groups with a determined incidence of 14.2% (15/106) for SSI. The results revealed that the SSI group had GNRI values that were significantly reduced compared with the non-SSI group (P<0.001). Receiver operating characteristic curve analysis was performed to determine the cut-off value of GNRI that conferred an increased risk of SSI; it was determined as 94 (sensitivity 80.0%, specificity 83.5%). Univariate analysis confirmed that a GNRI <94 was significantly associated with SSI (P<0.001), whereas multivariate logistic regression analysis revealed that a GNRI <94 was independently associated with SSI following PD (relative risk=1.73, 95% confidence interval=1.23-2.43; P<0.001). Therefore, a GNRI <94 is a potential predictive marker for SSI risk following PD.